New York Police Department Commissioner William J. Bratton announced this week that 2015 was the “safest year” in the city’s modern history. One indicator, he said: The number of reported sexual assaults spiked from 1,352 to 1,439.

“We had a significant increase in 2015 of rapes that were reported in previous years, in some instances going back many, many years,” Bratton said on the Brian Lehrer radio show.

A victim in Queens told police about a rape that happened in 1975, according to city data. Another in Brooklyn brought forward a 1999 assault. Another in Manhattan described an attack from 2003.

One-fifth of the rapes reported in 2015, it turns out, occurred sometime in previous years. (NYPD started tracking data on delayed reports, specifically, last year.)

Bratton called it “the Cosby effect.”

“Some of the rapes [Bill Cosby] is accused of go back 30 or 40 years,” he said. “We have really made a concerted effort to try and encourage the victims of rape to come forward.”

Law enforcement leaders say more rape complaints, in cities and on college campuses, is generally a good thing. That’s because the crime tends to be vastly underreported. About one in five women have experienced rape, according to the latest DOJ statistics. But federal researchers estimate that only 32 percent of rapes are reported to the police.

Cosby, meanwhile, faced his first criminal charge related to a sexual assault last week after Pennsylvania prosecutors said he drugged and raped former Temple employee Andrea Constand in 2004.  At least 50 other women have made similar accusations against him.


The New York Daily News cover illustrates the number of complaints against Cosby. (Courtesy of the New York Daily News)

Since the high-profile complaints started piling up, police departments in America’s largest cities have recorded an uptick in sexual assault reports. Officers in Los Angeles counted 1,626 cases in 2015, compared to 1,427 in 2014. Chicago saw 939 cases last year and 875 in 2014.

Though causation is impossible to prove, experts say the publicity around the entertainer’s downfall may have encouraged some victims to speak up about their own experiences.

Carol Tracy, executive director of the Women’s Law Project, said open dialogue is contagious.

"There is strength in numbers," Tracy said. “More women now are showing their faces, sharing their names and saying, ‘I was violated.' They see they have the right to come forward."

Rape remains one of the most underreported crimes because victims sometimes worry people won’t believe them, Tracy said. They may want to avoid judgement. They may fear retaliation from the assailant or, in high school settings, from peers.

Consider the West Virginia teenager who received threats on Twitter after the football players who raped her were found guilty of the crime. Or the British judge who publicly called a victim "extremely foolish" for drinking alcohol. The women who accused Cosby were widely ridiculed as "gold diggers" seeking fame.

"Rape, historically, has been a source of shame," Tracy said. "Victims have been profiled as liars."

The crime statistics have changed as American authorities update the way they investigate rape. Part of the reporting surge may stem from the FBI's decision to broaden its definition of rape in 2012, expanding from the "the carnal knowledge of a female, forcibly and against her will" to include other forms of assault -- such as unwanted oral sex and intercourse while one party is unconscious -- and male victims.

The White House announced a campaign to curb rape in 2014. The Justice Department released new guidelines last month for officers handling sexual assault cases, urging them not to assume a victim is an unreliable narrator.

“These assumptions,” Attorney General Loretta Lynch said at the time, “can send the case into a spiral of ineffectiveness, and the victim back into a spiral of despair and pain.”

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The disturbing truth about college football and rape

Why you should always buy the men's version of almost anything

Why Sweden just opened an emergency department for male rape victims